1. Field of the Invention
The present invention relates to electrical devices and, more particularly, to electrical devices, such as media players, that communicate with external devices.
2. Description of the Related Art
A media player stores media assets, such as audio tracks, that can be played or displayed on the media player. One example of a portable media player is the iPod® media player, which is available from Apple Computer, Inc. of Cupertino, Calif. Often a media player acquires its media assets from a host computer that serves to enable a user to manage media assets. The host computer can execute a media management application to acquire and manage media assets. One example of a media management application is iTunes® produced by Apple Computer, Inc.
Portable media players, such as MP3 players, are able to play music for users often via earphones or a headset. A portable media player typically includes one or more connectors or ports that can be used to interface to the portable media player. For example, the connector or port can enable the portable media player to couple to a host computer, be inserted into a docking system, or receive an accessory device. Typically, portable media players are dedicated to playing media. However, there exist today various different types of accessory devices that can be coupled to portable media players. For example, a remote control can be connected to the connector or port to allow the user to remotely control the portable media player. As another example, an automobile can include a connector and the portable media player can be inserted onto the connector such that an automobile media system can interact with the portable media player. As still another example, a microphone accessory device can be connected to a portable media player to enable voice recording. Yet still another example is a FM radio controller accessory that includes a FM tuner and a controller. Still yet another example is a camera connector that connects to a portable media player as well as a camera (via USB) and serves to facilitate transfer of images from the camera to the portable media player.
Currently, portable media players can interact with attached accessories in limited ways. However, as accessories become more complex and/or more integrated with operation of portable media players, more sophisticated interaction with accessories is required. Thus, there is a need for improved techniques to enable portable media players to communicate with accessory devices in accordance with a controlled protocol.